Spark plug



Mar. 13, 1923.

A. J. 'DONLEY SPARK PLUG Filed Aug. 18, 1920 Patented Mar. 13, 1923.;

umrso STATES ARTHUR J. DONLEY,

PATENT OFFICE...

or cnrcaeo, ILLINOIS.

SPARK PLUG.

Application filed August 18, 1920. Serial No. 404,382.

of Illinois, have invented a new and useful disconnected due tovibration and which will at all times maintain a good electricalconnection, although .readily' detachable without the use of tools.

One of the features of the invention resides in a sleeve or tubularmember em- .bedded in the insulating block of the plug, and forming asocket and an. electrode embedded, in the lower portion ofthe block withits upper end terminating at the lower end of said tube and insubstantial alinement with the longitudinal axis thereof, therebyforming an intensifying gap between the lowerend of the tube and theupper end of the electrode.

Another feature. of the invention resides in said tubular socket beingadapted to receive a plug terminal which. extends thereinto with africtional sliding fit thus enabling quick attachment and detachment ofthe terminal without the need of tools and the labor now required byother spark plugs, and eliminating washers; nuts, threaded rods andclamps which work loose through vibration and destroy the electricalconnection. 1

The invention further resides in the sundry details of construction,organization, and combination of parts hereinafter more fully described.

In this specification and the annexed drawings, the invention isdisclosed in the form in which it is considered to be the best, but theinvention is not limited to such form because it is capable of beingembodied in other forms; and it is to be understood that in and by theclaims following the description herein, it is intended to cover theinvention in whatever form it may embody'within the scope thereof.

In the drawings:

Figure 1 is a longitudinal sectional view taken through the spark plugconstructed in accordance with the invention,

-Fig. 2 is a transverse sectional view taken substantially on line 2-2of Fig. 1, and

Fig. 3 is a perspective view of the insulating block.

The s ark plug comprises a hollow metallic-mem er or casing 1,externally threaded at its inner end and provided at its opposite endwith a polygonal head. to recelve a wrench in the placing and removingof a plug. This casing has suitably secured to its lower end an inwardlylateral extending arm 2 PI'OVldlIlg one of the electrodes of the plug,in a manner which is usual in connection with the devices of thischaracter.

The insulating plug 3 is formed of fiber, porcelain or other suitablematerial, andhas an exterior contour which is common to most plugs, thatis having an enlarged central portion forming a shoulder 4', whichrests-on a shoulder 5 provided on the interior of the casing 1. Abinding nut 6 fits over the upper end of. the casing. This bindingnutengages on the opposite side a: of the shoulder 4, to clamp theinsulating block firmly in the casing against the shoulder 5 thereof,there being a suitable washer or gasket 7 between the shoulders 4 and 5so as to provide an air and gastight joint.

The insulating block is formed also with a longitudinal bore,substantially the upper half of the bore being enlarged, inthe mannershown in the drawings. A metallic tube 8, of any suitable material whichis a good electrical conductor is tightly fitted in the upper orenlarged portion of the bore and is held in place by cement or in anyother suitable'manner, the upperend of the tube 8 terminating and beingflush with the upper end of the insulating block.

In the lower portion of the bore is tightl fitted the other'electrode 9,of the plug en 7 as will be observed from the drawings, lies insubstantial alinement with the longitudinal axis of the tube 8, havingthe upper or inner end thereof terminating slightly with-, in the lowerend of the tubular member, while its lower end projects for a distancebeyond the lower end of the insulatin block to cooperate with theelectrode 2 for the purpose of producing an electrical spark forigniting the exp osive mixture in the combustion chambers of theengines.

It will be observed that the tubular member 8 provides a socketto'receive 'a connecting terminal, and, by reason of its disposition andrelation relative to the electrode 9, an

auxiliary spark gap is provided between its lower end and'the upper enda of the electrode 9, which intensifies the spark occurring at the point6 in the combustion chamber. It will also be observed that theconstruction of the insulating block, just described, is extremelysimple, possessing but three elements which may be assembled withextreme ease without necessitating skilled workmen and can be producedat a very low. cost, while at the same time provides a spark plug with'an intensifying gap which has heretofore only been provided withconsiderable additional cost.

The tubular or socket member 8 receives the projecting end 10 of a plugterminal 11. The end 10 of the terminal preferably has the same crosssection as the socket and is of any suitable conductive material and issuitably slotted as at 0, to give it a lateral resiliency in order thatthe end 10 will tightly and frictionally engage the interior wall of thesocket 8. This connection of the terminal 11 with the spark plug permitsof a rotating or oscillating movement between the end 10 of the terminaland the socket, thereby having a free movement to compensate for anytorsional twist, or strain on the terminal caused by vibration.,Moreover, this terminal connection permits ready attachment anddetachment of it from the spark plug by a mere longitudinal pull on theterminal and eliminates all nuts, washers, threaded rods, clamps andother similar cap members which require considerable effort and tools tomanipulate. Furthermore, the ordinary spark plu having clamps andscrew-threaded parts or securing the terminal to the plug, requireconstant attention because the terminal works loose by reason of thevibration set up by the engine and traction, and destroys the electrical00111160- tion. It is readily appreciated that this is the source ofconstant annoyance and often causes the engine to knock and jolt, andthe operator usually goes to considerable work and inspection before hehas realized that the trouble is due to a loose connection with a sparkplug.

,ese

By reason of this terminal connection the liability of short-circuitingis largely. reduced because the insulated and enlarged handle portion dof the terminal overlies the upper end of the tubular socket 8, andabuts the upper surface of the insulating block 3, as clearly shown inFigure 1. In the usual type of spark plug the opposite end of theelectrode projects from the upper end of the insulating block, andshould a tool or other piece of metallic material come in contacttherewith it short-circuits the spark plug. Moreover the upper end ofthe electrodes in the usual spark plug very often becomes broken ofi andthereby destroys the plug.

From the foregoing it will be apparent that the spark plug according tothe present invention is extremely simple and'that the tubular member 8forms a two-fold purpose of providing a socket having an improvedterminal connection with the plug, and for providing an intensif ing gapfor the current. It will further e apparent that after the life of theplug of this invention, the entire plug need not be discarded, but maybe repaired by simply removing the lock-nut 6 and then withdrawing theinsulating block 3, which is extremely inexpensive and may be suppliedat one-fourth the cost of new plu s.

Vhat claim is:

1. As an improvement in spark plugs, an insulating block, an electrodein said block, an electro-c'onductive tubular member forming a terminalsocket in said block and spaced from the electrode to provide anintensifying gap with the latter, and an electro-terminal plug removablyinserted in said tubular socket and in electrical contact therewith andout of contact with said electrode. 2. As an improvement in spark plugs,an insulating block, an electro-conductive tubular member forming aterminal socket in said block, an electrode in said block and arrangedin substantial alinement with the longitudinal axis of the tubularmember and entering the lower end of the socket for providing anintensifyin gap, and an electro-terminal plug remova ly inserted in saidsocket.

3. As an improvement in spark plugs, an insulating block, anelectro-conductive tubular member forming a terminal socket in saidblock, and an electrode in said block having its inner end extending inthe inner end of said tubular member for providing an intensifying gapwith'the latter, and an electro-terminal therewith and out of contactwith said electrode.

4. As an improvement in spark plugs, an

insulating block having alongitudinal bore tive to each other to providean intensifytherein, the upper portion of said bore being ing gap and anelectro-terminal plug removenlarged, an electro-conductive tubularmemably inserted in said tubular member. 10 ber secured in the enlargedportion of the .In testimony whereof I have hereunto set bore, anelectrode in the smaller portion of my hand.

said bore, the inner ends of said tubular member and electrode beingpositioned rela- ARTHUR J DONLEY.

